1. Field of the Invention
The present invention relates to an optical instrument having a zoom function for varying focal length of an imaging optical system, and being capable of moving a plurality of zoom lens groups independently, and an imaging device.
2. Description of the Related Art
A zoom lens having a first cam region of a zoom region for causing movement of a zoom lens group, and a second cam region, extending from an end part of the first cam region, for causing movement of a lens group to a macro position where macro shooting is possible, formed in a lens barrel as a continuous cam, is known (refer to Japanese patent laid open number 2003-279836 (hereafter referred to as patent publication 1)).
Also, in order to achieve size reduction of a lens barrel, it has been proposed, instead of a mechanical cam, to drive a front group and rear group of lenses by respective independent motors. For example, Japanese patent laid-open No. Hei. 6-324245 (hereafter referred to as patent publication 2) discloses, in a zoom lens having a front lens group and a rear lens group, a zoom lens unit having a front lens group drive motor and a rear lens group drive motor, and carrying out a zoom operation by driving both motors together when a power supply voltage is greater than or equal to a specified value.